Re: Very slow queries
От | Ted Allen |
---|---|
Тема | Re: Very slow queries |
Дата | |
Msg-id | 45C0A88B.2060409@blackducksoftware.com обсуждение исходный текст |
Ответ на | Re: Very slow queries (Sidar López Cruz <sidarlopez@hotmail.com>) |
Ответы |
Re: Very slow queries
(Sidar López Cruz <sidarlopez@hotmail.com>)
Re: Very slow queries (Sidar López Cruz <sidarlopez@hotmail.com>) |
Список | pgsql-performance |
How many rows were delete last time you ran the query? Chad's query looks good but here is another variation that may help. Delete From ceroriesgo.salarios Where numero_patrono In (Select ceroriesgo.salarios.numero_patrono From ceroriesgo.salarios Left Join ceroriesgo.patronos Using (numero_patrono) Where ceroriesgo.patronos.numero_patrono Is Null) Hope that Helps, Ted Sidar López Cruz wrote: > > > >> From: "Chad Wagner" <chad.wagner@gmail.com> >> To: "Sidar López Cruz" <sidarlopez@hotmail.com> >> CC: pgsql-performance@postgresql.org >> Subject: Re: [PERFORM] Very slow queries >> Date: Tue, 30 Jan 2007 17:37:17 -0500 >> >> On 1/30/07, Sidar López Cruz <sidarlopez@hotmail.com> wrote: >>> >>> query: Delete From ceroriesgo.salarios Where numero_patrono Not In >>> (Select >>> numero_patrono From ceroriesgo.patronos) >>> >>> Seq Scan on salarios (cost=51021.78..298803854359.95 rows=14240077 >>> width=6) >>> Filter: (NOT (subplan)) >>> SubPlan >>> -> Materialize (cost=51021.78..69422.58 rows=1032980 width=25) >>> -> Seq Scan on patronos (cost=0.00..41917.80 rows=1032980 >>> width=25) >>> >> >> How many rows exist in salarios, but not in patronos? How many rows are >> there in salarios? > > Rows: > Patronos: 1032980 > Salarios: 28480200 > >> >> What does the explain look like for: >> >> delete >> from ceroriesgo.salarios s >> where not exists (select 1 >> from ceroriesgo.patronos >> where numero_patrono = s.numero_patrono); >> >> Also, is this not a case for a foreign key with a cascade delete? > > No, this is not cascade delete case because I need to delete from > salarios not from patronos. > > >> http://www.postgresql.org/docs/8.2/static/ddl-constraints.html >> >> >> -- >> Chad >> http://www.postgresqlforums.com/ > > _________________________________________________________________ > Charla con tus amigos en línea mediante MSN Messenger: > http://messenger.latam.msn.com/ > > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend > -- *Edward Allen* Software Engineer Black Duck Software, Inc. tallen@blackducksoftware.com <mailto:tallen@blackducksoftware.com> T +1.781.891.5100 x133 F +1.781.891.5145 http://www.blackducksoftware.com
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